Connection and elbow in a gas appliance

ABSTRACT

A connection is provided whereby a first tube, which may be bent into an elbow, has at least one end flow drilled. During the flow drilling process the first end is shortened, reduced in thickness, and most importantly, the inner diameter is increased to accept a second tube. Before connecting the second tube, the first end is preferably tapped with threads which can receive a nut and the nut captures an end of the second tube, preferably entrapping one of at least one bead and a ferrel to provide a connection.

CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional PatentApplication No. 61/534,069 filed Sep. 13, 2011, incorporated herein byreference in its entirety and is a divisional application of Ser. No.13/613,851 filed Sep. 13, 2012.

FIELD OF THE INVENTION

The present invention relates to a connection for connecting tubes orpipes together in fluid tight engagement, such as for specialapplications, and more specifically to connecting an aluminum pipe to asteel elbow which provides gas internally to a broiler element in a gasoperated stove.

BACKGROUND OF THE INVENTION

Elbows for use in gas ovens with broiler elements have been used for anumber of years. Some competitors provide brass castings for this part.Others, such as the applicant, provided stainless steel elbows whichrequired numerous welding steps to form up components to be able tocooperate with an air shutter at one end internal to the oven as well asan aluminum pipe providing fuel to the elbow external to the heatedspace in the oven. Since many gas oven with broil elements areself-cleaning ovens capable of reaching temperatures exceeding 800-900degrees Fahrenheit, the aluminum piping external to the oven is notnormally located in the high temperature heated space. Furthermore,harsh cleaning chemicals are also not wisely applied to aluminum.

Machining and/or forming these prior art parts has been proven to berelatively expensive. In the prior art, a welded fitting is provided andfitting up with an outer thread fitting. This machined fitting providedmale external threads which cooperated with internal female threadsconnected to a connector aluminum tube such as with a compression nutand sleeve or a ferrule style connection arrangement. The fitting waswelded to the end of a steel tube forming the elbow. On the other end,external threads were machined into the outer surface of the pipe elbowto cooperate with internal threads of a brass orifice.

A need exists to find at least a simplified connector constructionand/or elbow construction for the market place.

SUMMARY OF THE INVENTION

It is a present object of the present invention to provide an improvedelbow and/or connection system for joining pipes or tubes together.

It is an object of the present invention to provide an improvedconnection such as from stainless steel to aluminum with a fluid tightconnection.

It is a further object of many embodiments of the present invention toprovide an improved elbow connection which provides improved connectionsconnecting steel pipe to aluminum pipe at their respective ends in fluidtight engagement.

Accordingly, in accordance with the presently preferred embodiment ofthe present invention, an elbow connection commonly utilized with gasovens such as those providing a broiler element is provided. In thesestyle ovens, it is common to use aluminum tubing external to the ovenchamber to direct the flow of gas received from a gas source to thestove whether natural gas or propane. However, when entering the ovenheated area, the temperatures and environment internal to the oven, suchas a self-cleaning oven, could be rather hostile to aluminum and thus atransition to stainless steel (or brass as provided by competitors)often occurs. In order to provide a component which can withstand thehigher temperatures and/or harsh corrosive environment possiblycontributed to by cleaning chemicals often utilized in ovens, a newelbow is contemplated with at least one improved connection.

In order to make the connection with a new elbow at an external ovenconnection, a stainless steel tube of a constant diameter is preferablyflow drilled in the present instance from having an outer diameter ofabout ⅜ of an inch to having an outer diameter of about 0.616 incheswhich is almost doubling the outer diameter. In order to accomplish thisflow drill process, a rapidly rotating drill bit expands the materialwhile the end is compressed. In making this end, a tube is compressed by0.075 inches. As it expands, its wall thickness changes from about 0.065inches to about 0.040 inches. The inner diameter at the end thusincreases relative to the diameter of the untreated section of the pipeby roughly doubling as well.

Within this larger open end, internal threads are tapped into aninterior wall. A compression nut provided about an external portion ofan inserted aluminum tube with external threads cooperates with theinternal threads of the elbow connector portion. Between the compressionnut and the end of the inserted tube is at least one of a singleexternal bead, multiple external beads such as double bead, or a ferrulesuch as a brass ferrule which can compress against the tapering internalwalls of the expanded end as the nut is screwed into the internalthreads of the larger opening end.

An intermediate portions of the elbow can be flanged to cooperate with aconnection of the oven wall and the other end of the elbow can haveinternal threads which can cooperate with external threads on a nozzleorifice which is preferably spaced from a conical section of the nozzleorifice which can then compress against an end surface of the pipe ortubing once installed to form a fluid tight seal. The nozzle orifice canthen be connected to an air shutter to provide air gas mix to the boilerburner located downstream. A bend normally occurs between the two ends.This elbow construction provides advantages of prior art constructionsand is believed to require fewer machining steps and/or provides simplermachining efficiency and/or a likely higher quality control capabilitythan other designs.

BRIEF DESCRIPTION OF THE DRAWINGS

The particular features and advantages of the invention as well as otherobjects will become apparent from the following description taken inconnection with the accompanying drawings in which:

FIG. 1 shows an external side plan view of the presently preferredembodiment of the present invention;

FIG. 2 shows a side partially cut-away view showing the connection ofthe construction of FIG. 1 to a cooperating tube;

FIG. 3 shows a side partially cut-away view showing a firstalternatively preferred embodiment showing connection of FIG. 1 to acooperating tube;

FIG. 4 shows a cross-sectional view of the elbow of FIG. 1 prior toconnecting to an orifice; and

FIG. 5 shows a cross-sectional view of an orifice connected to a secondend of the elbow as shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a first presently preferred embodiment of the presentinvention in the form of an elbow 10 such as an elbow tube as utilizedwith broiler burners in a gas stove. As discussed above, the elbows,such as elbow 10, are utilized to transition from external to internalto the oven compartment particularly for self-cleaning ovens withbroiler elements which can often reach temperatures of about 900 degreesFahrenheit or more and also be subjected to harsh chemicals such as ovencleaner chemicals inside the oven. An aluminum element would not farewell in such an environment.

Accordingly, the preferred embodiment is preferably made of steel suchas cold-rolled steel which has been treated such as with a chromeplating process or other appropriate pre-selected material. Otherappropriate materials may be utilized with other embodiments. Elbow 10is comprised of a tube 12 having a first 14 and a second end 16. Betweenfirst and second ends 14,16, there is normally a bend 18 such as anelbow bend as illustrated. Flange 21 is also normally provided withbores 15,17 shown in phantom to connect to an internal oven wall (notshown) or other connection location.

First and second segments 20,22 on either side of the bend 18 and/orflange 21, if provided, can be provided as required by manufacturers toaccommodate particular styles of oven equipment. Other segments could beprovided and/or other design criteria accommodated with otherembodiments. First segment 24 of first tube 12 preferably provides anoutwardly flared segment extending from first portion 20 to a secondsegment 26. Second segment 26 is preferably provided with internalthreads 28 which can be tapped to provide an internally threaded secondsegment 26 after providing the outwardly flared first segment 24.

Internal or inner surface 30 of outwardly flared first segment 24preferably is at least relatively smooth if not deburred, if necessary,so as to be in a proper condition as will be described in further detailbelow. The applicant has manufactured the elbow 10 by taking a straightsegment of stainless steel tubing, bending it to provide bend 18, andutilizing a flow drill to compress and expand the first end 14 toprovide the outwardly flared segment 24 as well as the second segment26. Second segment 26 may then be tapped to provide internal threads 28.Second segment 26 may have a relatively consistent inner and/or outerdiameter as shown or taper like first segment 24 for other embodiments.

In performing the flow drill process, the 0.065 thickness of first pipewall portion 32 is transitioned to about a 0.040 thickness at secondpipe wall portion 34. Thus, a wall reduction of somewhere between about25% to 50% occurs, and more thoroughly about ⅓ of the thickness of thewall decreases at least in some portion of a first segment 24, andsecond segment. Furthermore, as this process occurs, the length isshortened at the first end 14 as first end 14 is compressed towards thesecond end 16 during the flow drilling process. A shortening of about0.075 has been measured during this process. Outwardly second segment 26may have a relatively constant internal diameter particularly aftertapping, such as about 0.58 which stands in contrast to the innerdiameter of about 0.25 of tube segments 20,22. The inner diameterincreases from roughly doubles and preferably increases the fact ofsomewhere between about 1.5 times the original inner diameter to aboutthree times, and more preferably, about two times the inner diameter.After tapping second segment 26 can cooperate with a 7/16 externalthreads shown as nut threads 36 provided a nut 40. One will note thatnut 40 is identically shown in the various embodiments as is theconstruction of the first end 14. Other nuts 40 could be provided withother embodiments.

The difference in the embodiments of FIG. 2 and FIG. 3 is that theconnections for other connected tube 42,44 are slightly different. Arelatively straight segment of the tube 44 is illustrated for a firstconnection. A ferrule 46 is shown provided towards the first end 48 andthen as the compression nut 40 is directed by screwing its threadsrelative to the second segment 26 and outwardly flared section 24 toprovide a fluid tight seal against the inner surface 30 of the firstsection 24. The ferrule 46 is simultaneously compressed against theexterior surface 43 of the tube 44. The first end 48 of the tube 44 mayalso contact the internal surface 30 of the second segment 26 to assistin providing a fluted tight seal as well.

In the presently preferred embodiment of FIG. 2, one or more beadsillustrated as first and second beads 60,62 can be provided toward afirst end 64 of tube 42. More or fewer beads 60,62 may be provided inother embodiments. In this construction, the first tube 42 effectivelyprovided with a built in ferrule. As the compression nut 40 is tightenedwith threads 36 relative to threads 28, at least one bead 62 is placedin contact with the inner surface 30 of the outwardly flared firstsection 24 and possibly in combination with the first end 64 contactinginternal surface 30 to provide a fluid tight seal. Other beads such asfirst bead 60 could also contact inner surface 30. In this embodiment,the only possible source of fluid leakage is past the external portionof first bead 62. In the embodiment of FIG. 3, a leakage could occuralong internal surface 70 of the ferrule 52 as well as along an externalsurface 72 of the ferrule 52. Providing one or more beads such as 60,62is a process discussed in various other patents other than that of theapplicant such as U.S. Pat. No. 5,573,285 and others.

The second end 16 may be machined to provide inwardly directed threads81 which can then cooperate with a screw in orifice 80. Orifice 80 mayhave outwardly directed threads which can provide a situation where thesecond end 16 is internally tapped such as to provide 5/16 threadsinternal to the inner bore. Then, a cooperating orifice 80 such as shownin FIG. 5 can be screwed therein with outwardly directed threads 82. Theinwardly directed threads 84 at the second end 16.

In addition to having the outwardly directed threads 82, the outwardlydirected threads 82 are preferably spaced by channel 86 from first rowconical section 88 which may begin radially at the termination of thethreads 82 and can extend radially outwardly preferably at least asubstantial portion of the thickness of the tube portion 22, if not pasttube portion 22 so that when the orifice 80 is screwed on to the secondsection 22, the first conical section 88 effectively forms a seal at thesecond end 16 as shown in FIGS. 1 and 5 to form a fluid tight seal. Theflats 90 can cooperate with a wrench to provide the appropriate amountof torque. The orifice 80 provides a measured flow path to a air shutter(not shown) internal to an oven and to provide a fuel/gas mixture to aninternal broiler element for use by a gas oven.

Numerous alterations of the structure herein disclosed will suggestthemselves to those skilled in the art. However, it is to be understoodthat the present disclosure relates to the preferred embodiment of theinvention which is for purposes of illustration only and not to beconstrued as a limitation of the invention. All such modifications whichdo not depart from the spirit of the invention are intended to beincluded within the scope of the appended claims.

Having thus set forth the nature of the invention, what is claimedherein is:
 1. A method of manufacturing an improved connectioncomprising: proving a steel length of a first tube; at a first end ofthe first tube, flow drilling the tube at a first end to a wallthickness reduction of at least about 25% while increasing an innerdiameter at the first end, and then tapping internal to the first end toprovide threads.
 2. The method of claim 1 further comprising the step oftapping the second end with a smaller diameter than the first end. 3.The method of claim 1 wherein during the step of flow drilling, reducingthe wall thickness at least 50%.
 4. The method of claim 1 wherein duringthe step of flow drilling, shortening the tube while increasing theinner diameter during the flow drilling step.
 5. The method of claim 1further comprising the step of capturing a second tube at the first endwith a nut screwed into the threads.
 6. The method of claim 5 whereincaptured second tube has one of at least one bead and a ferrel about anexterior surface near an end of the second tube and the one of the atleast one bead and the ferrel are located intermediate the exterior ofthe second tube and the first end of the first tube when captured. 7.The method of claim 6 wherein the second tube has a similar outerdiameter as the first tube prior to flow drilling the first end of thefirst tube.
 8. The method of claim 1 wherein the first tube provided issteel.
 9. The method of claim 1 further comprising the step of bendingthe first tube at an elbow.